The United States planned to send nearly a quarter of a billion dollars to Yemen this year. Its fate depends on whether the State Department calls a coup a coup.

When is a coup a coup? When it comes to Yemen, the answer could determine the future of hundreds of millions of dollars of American aid to a country on the frontline of a fight against the world’s most dangerous branch of al Qaeda.

Washington has sent more than $1.4 billion in economic and military assistance to Yemen since 2009 to help the impoverished country fight militants from al Qaeda in the Arabian Peninsula, a group known — and feared — for its bomb-making prowess.

The United States was slated to send Sanaa almost a quarter billion dollars more this year, but the aid spigot could be shut off if the Obama administration determines that the apparent overthrow of the Yemeni government by Shiite Houthi rebels constitutes a military coup.

On the surface, that seems like an easy call to make. On Tuesday, insurgents stormed Yemen’s presidential palace, finishing what seems to be about of the government of President Abed Rabbo Mansour Hadi, whose current whereabouts are unknown. The country’s information minister told CNN it was “the completion of a coup.”

The Pentagon sent warships to the region to potentially evacuate American diplomats and citizens, but the State Department is so far refusing to use the word coup.

“We are deeply concerned about the turn of events in Yemen over the last few days, including the ongoing attack on the Presidential palace, and call for immediate cessation of hostilities,” a State Department official said in an email to Foreign Policy.

The administration would be loath to use the word coup for a very simple reason: under American law that would require an immediate cut off of American aid to the country. The White House faced a similar dilemma when the Egyptian military ousted former Egyptian President Mohamed Morsi. It ultimately decided not to use the word, and the aid money kept flowing.

In the case of Yemen, the Hadi government has been a flawed but relatively steady ally of the U.S. in the fight against AQAP, the group that’s made claims of responsibility for the recent Charlie Hebdo attack in Paris. He has been under siege by Houthi forces representing Yemen’s Shiite minority for months. Tuesday, he lost his tenuous grip on power as his palace fell.

Washington is slated to give him $232 million in civilian and military aid; calling recent events a coup would keep that money from being sent over.

That would come on top of the eye-opening amount of aid to Yemen in the past five years. According to a November 2014 Congressional Research Service report, the majority of the $1.4 billion sent by the United States to Yemen from 2009 to 2014 has come from the State Department and the United States Agency for International Development. During that same period the Defense Department gave Yemen about $370 million of the total amount to take on AQAP.

Whatever it’s officially termed, Hadi’s disappearance represents a blow to American anti-terror efforts in the Middle East. President Barack Obama has often cited Yemen’s campaign against AQAP as a successful example of his soft-power approach to fighting terrorism.

“What really matters is the Hadi government has been an ally against AQAP,” Christopher Swift, a Yemen expert at Georgetown University told Foreign Policy. “They have been helpful to us in taking the war to the group on the ground.”

The White House is taking precautions in case embassy staff needs to be evacuated from Sana’a. Two U.S. Navy warships moved to new positions in the Red Sea Monday to more quickly get American staffers out.

It already appears as if American staff is in some danger. On Tuesday, the embassy announced shots were fired at one of its vehicles Monday night. Senator Dianne Feinstein, the ranking Democrat on the Senate Select Committee on Intelligence, has called on State to orders its workers to leave.

The State official said there are currently no plans to evacuate.

“We are continuing to closely monitor developments in Yemen and will adjust the embassy’s security posture response in accordance to the situation on the ground,” the official said.

Tuesday’s events follow months of tension between Hadi’s government and the Houthis, who want a greater say in how the country is run. Last year, members of the group stormed Sana’a, resulting in violence that left 300 dead. Last September, the two sides signed a ceasefire agreement that allowed Houthis to take positions of power within the Yemeni government. However, strains were renewed recently when presidential Chief of Staff Ahmed bin Mubarak was abducted because Hodi planned to introduce a new constitution without getting the Shiite group’s seal of approval.

Now, more violence is all but inevitable. “Going for the presidential palace and the formal institutions of Yemeni politics, its the antecedent to a civil war,” Georgetown’s Swift said.